Predicting Storms in Oklahoma

In Oklahoma, "where the wind comes sweepin' down the plain," April through June means thunderstorms, huge ones that dump inches of rain in a few hours, swelling streams and flooding crops, businesses and homes. Storm season in Oklahoma also brews the ominous dark funnels that can smash houses flat in seconds.

During the 1995 storm season, ARPS ran on the scalable, parallel CRAY T3D system, allowing the model to run at full capacity and yield predictions in an hour or less, a shorter time than previously possible. Drawing on this computing capability, ARPS marked a milestone in meteorology by successfully predicting the structure and location of individual thunderstorms six hours in advance. This is the first time anywhere this has been accomplished.

Numerical Forecast versus Radar for June 8, 1995.

The ARPS forecast (left) created at 1 p.m. for conditions at 7 p.m. compares well with a radar image at 7 p.m. (right). Color indicates rainfall intensity, increasing from light blue to pink.

This animation, created with ARPS storm forecast data, shows development of a thunderstorm over Oklahoma. It covers a surface area 67 kilometers square extending 17 kilometers in altitude. The white isosurface shows high concentrations of combined cloud and rain water. The red isosurfaces represent columns of high vorticity, which have the potential to spawn tornadoes. The blue ribbons show wind velocity at two planes, about 600 and 4,800 meters above ground level.